Fuse device for high-voltage circuits



Oct. 17, 1950- H. KOTT 7 2,526,370

FUSE DEVICE FOR HICH-VOLTAGE CIRCUITS Filed D96; "30," 1949 20 Fig 3 B a W.

i' I III (13 V 3 I i I 2 l l 12 IO 6 FIG 5 H IO A INVENTOR.

5 Hermann KoH 8Y4 m @M ATTORNEY Patented Oct. 17, 1950 UNITED STATES PATENT OFF ICE FUSE DEVICE FOR HIGH-VOLTAGE CIRCUITS 3 Claims.

This invention relates to electrical fuse devices and more particularly to a fuse adapted for the protection of electric circuits carrying high voltage current and has for its object the provision of a gaseous conduction fuse device having a replaceable fuse element therein and adapted for the protection of high voltage transformers.

Another object is to provide a fuse device for high voltage transformers which is adapted to be electrically connected in series with the primary winding of th transformer and which contains a gaseous conduction discharge device having a determined break down voltage between the electrodes thereof one of which electrodes is connected electricallyto the high voltage side of the transformer and the other being removable and replaceable and being electrically connected to ground potential, the said other electrode being substantially immediately destructible in the gaseous conduction discharge between the electrodes and mechanically arranged to operate to open the primary circuit immediately on destruction of the said electrode.

Still another object is to provide a safety fuse element for high voltage electrical circuits and devices and particularly for high voltage transformers.

Other objects will be apparent as the invention is more fully hereinafter disclosed.

This invention is an improvement of the inven tion described and claimed'inrmy prior application bearing Serial No. 719,563, filed December 31, 1946, and entitled Safety Fuse for High Voltage Transformers.

In accordance with the objects of the invention I have invented an improved safety fuse device for use in the protection of high voltage electrical circuits and devices, such as high voltage transformers, in which a spring actuated make and break switch means is arranged for electrical connection in series in the primary or low voltage circuit of a high voltage transformer and a gaseous conduction discharge device having adjustable electrodes to obtain a determined space gap with resultant determined break-down voltage therebetween is arranged for electrical shunt connection in the secondary or high voltage side of the transformer, the ground potential electrode in the said discharge device being one that is replaceable and destructible substantially immediately in the gaseous conduction discharge between theelectrodes and being operatively connected mechanically to the said switch means as to maintainthe switch in closed position until destroyed by a gaseous conduction discharge between the electrodes.

As one specific embodiment of th present device, but not as a limitation thereof, I have illustrated in the drawings one species thereof which is particularly adapted for permanent installation in a high voltage electrical circuit, such as a fluorescent lamp circuit energized by a high voltage transformer drawing current from the usual 110 volt A. C. supply line.

Referring to the drawings:

Fig. 1 is a side elevational view, partly cut away, of the device of the present invention;

Fig. 2 is an end elevation of the same;

Fig. 3 is a top view of the device with the cover removed showing the elements in circuit closing position; s

Fig, 4 is a partial top view of the device with the cover removed, showing the element in circuit opening position;

Fig. 5 is a diagrammatic view showing the device in operative combination with the primary and secondary windings of a high voltage transformer; and

Fig. 6 is a perspective view of the replaceable fuse electrode of the present device.

As may be recognized from the drawings, the electrical fuse device of the present invention consists of a spring actuated make and break switch S and means for electrically connecting the switch in series with the primary winding l of the transformer T, and a gaseous conduction discharge device including electrodes A and B, electrode A being electrically connected to the high voltage circuit including winding 2 of the transformer T and high voltage lamp 3 and being adjustable towards and away from electrode B to obtain a determined space gap therebetween, and electrode B being removable and consisting. of a relatively small diameter electrically. conducting fuse wire 4 tensionally sustained between spring arms 5 and 6 lying in side grooves 1-7 and held in position therein by pins 8 8.

As indicated in the drawings, the switch S is provided with spring arms ill-4G on opposite sides thereof, one arm I0 overlying the pin ll actuating the make and break elements l2--l3 of the switch, the space gap between arms 5 and 6 and arms lU-l 0' being'that providing for the engaging of the arms, when the fuse element B is mounted in position, for closing of the switch S by the inward movement of arm [0 into contact with pin H and for the release ofarm I0 and the reverse movement of pin 1 l upon the destruc- 3 tion of the fuse wire. 4 upon an electrical discharge between electrodes A and B.

To facilitate the initiation of a gaseous conduction discharge between electrodes A and B, arm is mounted in electrically insulated relation to the switch S and is electrically grounded substantially as indicated in Fig. 5, the pin Ii being electrically insulated from spring contact member l2 of the circuit make and break means I2 and i3.

To facilitate inspection of the device and to determine operativeness of the same, a glow discharge lamp L and high resistance R are series connected electrically in parallel with the switch S in the primary circuit of the transformer which lamp is designed to operate at voltages approximating the line voltage in the primary circuit when the full line voltage passes therethrough .upon the opening of the switch S.

, Switch S is secured by means of bolts 2! in fixed position upon a base comprised of electrical insulating material such as a molded plastic or hard rubber composition old, per se, in the art and a cover 22 is provided for seating on the base 20 to enclose the switch S and removable electrode B from the atmosphere. Electrode A is mounted through the cover 22, substantially as indicated, in a porcelain housing 23 having a removable top section 24 to permit for the ready adjustment of the electrode A in the housing 23 towards and away from electrode B to obtain a determined space gap therebetween.

One of the most important features of the present invention is the provision of tubular extension 25 of the porcelain housing 23 about and beyond the end of electrode A. This tubular extension 25 is provided to contain the gaseous conduction discharge between the electrodes A and B and to direct same onto the fuse wire 4 of the electrode B in concentrated form.

As may be recognized the gaseous conduction discharge between electrodes A and B is obtained through air at atmospheric temperature and pressure and the adjustability of electrode A is required to obtain the proper space gapat any given atmospheric temperature and pressure for the gaseous conduction discharge between the electrodes A and B at any desired liminting voltage in the secondary circuit of the transformer T. The proper space gap to provide is well within the skill of one skilled in the art based upon known and published data in engineering tables. As an example, for a limiting voltage of 12,000 volts on the secondary winding of the transformer I provide a space gap of 10 millimeters between electrodes A and B where the fuse device is to be used in locations below an altitude of 5,000 feet above sea level.

Also as indicated in the drawings, electrode B is removable and replaceable being insertable in a suitable recess provided therefor in the enclosing housing consisting of base 20 and cover plate 22, substantially as shown. Electrode B is comprised of molded insulating material of the same composition employed in the base and cover plate parts 20 and 22 and is preformed to fit in the recess provided to locate the fuse wire l directly under the end of electrode A.

The wire 4 may be of a wide number of electrically conductive compositions without essential departure from the invention. The most satisfactory fuse wire, however, is one that possesses high tensile strength in the cold and a rapidly lowering tensile strength with increase in temperature so that rupture of the wire 4' by the spring tension of arm in will occur substantially immediately after the gaseous conduction discharge is initiated between electrodes A and B. In the specific embodiment illustrated, which is adapted for the protection of high voltage transformers utilized in high voltage circuits including a fluorescent lamp 3, the fuse wire 4 which I have found to be most satisfactory is one comprised of A millimeter diameter wire consisting of the metal bronze.

It is believed apparent from the above disclosure of the present invention that the same may be widely modified without essential departure therefrom and all such modifications and departures are contemplated as may fall within the scope of the following claims:

What I claim is:

l. A fuse device for high voltage electrical circuits, said device comprising, in combination, a gaseous conduction discharge device having two spaced electrodes therein, one being adjustable toward and away from the other to provide a desired. space gap and break down voltage therebetween, and said other electrode being stationary and consisting of a length of wire held in tension between spaced apart spring arms, a make and break switch, and a second pair of spring arms disposed in a position to be engaged by the first mentioned spring arms while the latter are in tension engagement with said wire and to actuate the switch to closed position when so engaged by the first mentioned spring arms, and to actuate the said switch to open position when the first mentioned spring arms are not in tension engagement with the said wire. I

2. A fuse device for high voltage electrical circuits, said device comprising a housing of insulating material having an opening in a wall thereof, a gaseous conduction discharge device having two electrodes, one of said electrodes including a plate of insulating material of general rectangular form and of a size to removably fit into said opening in the wall of the housing and be supported therein, a pair of oppositely disposed spaced spring arms each secured at one end to said plate at one side thereof and projecting forwardly from the inner end of the plate, and a length of fusible wire connected at opposite ends to said arms and held in tension therebetween, the other electrode of said last mentioned device being mounted on and extending into the housing with its inner end spaced from the fusible wire of the other electrode, a normally closed mechanically actuated make and break switch, and spring means actuated by the initiation of a gaseous discharge between said spaced electrodes to actuate said switch from closed to open position.

3. A fuse device for high voltage electrical circuits,said device comprising a housing of insulating material, an elongated tubular part of insulating material on a wall of the housing extending transversely thereof and providing a chamber interiorly thereof communicating with the interior of said housing, a gaseous conduction discharge device having two spaced electrodes, one of said electrodes comprising a pair of oppositely disposed spaced spring arms supported on a wall of the housing and extending into the housing, and a length of fusible wire connected at opposite ends to and held in tension between said spring arms, the other electrode consisting of a metal rod mounted in said tubular part on the housing and having its inner end projecting into the housing near to an intermediate portion of said fusible Wire,.said tubular part having an inner extension portion extending inwardly beyond the inner end EN ITED of the rod electrode mounted in said tubular part REFER CES C to contain a gaseous conduction discharge bee following references are of record in the tween the electrodes and direct the same in confile of thls pa-tent? centrated form onto said fusible wire electrode, a 5 UNITED STATES P ENT make and break switch, and a mechanical connection between said spring arms and said switch gg f B Name M g 81932 to maintain said switch in closed position while 2146498 g j 25 1939 said fusible length of wire is held in tension be- 2:463:812 Seaman Mar 811949 tween said spring arms, and in open position 10 when the spring arms do not hold the wire in tension therebetween.

HERMANN KOTT. 

